Method to make an integrated side shield PMR head with non conformal side gap

ABSTRACT

A non-conformal integrated side shield structure is disclosed for a PMR write head wherein the sidewalls of the side shield are not parallel to the pole tip sidewalls. Thus, the side gap distance between the leading pole tip edge and side shield is different than the side gap distance between the trailing pole tip edge and side shield. As a result, there is a reduced side fringing field and improved overwrite performance. The side gap distance is constant with increasing distance from the ABS along the main pole layer. A fabrication method is provided where the trailing shield and side shield are formed in the same step to afford a self-aligned shield structure. Adjacent track erasure induced by flux choking at the side shield and trailing shield interface can be eliminated by this design. The invention encompasses a tapered main pole layer in a narrow pole tip section.

RELATED PATENT APPLICATIONS

This application is related to the following: Docket #HT06-036, Ser. No.11/787,015, filing date Apr. 13, 2007; and Docket #HT07-050; Ser. No.12/072,272, filing date Feb. 25, 2008; both assigned to a commonassignee and herein incorporated by reference in their entirety.

FIELD OF THE INVENTION

The invention relates to a non-conformal integrated side shield PMR headstructure and a method for forming the same in which a side shield andtrailing shield are formed in one process step so that side fringing isminimized and an acceptable overwrite level is maintained.

BACKGROUND OF THE INVENTION

Perpendicular magnetic recording (PMR) has been developed in part toachieve higher recording density than is realized with longitudinalmagnetic recording (LMR) devices and is believed to be the successor ofLMR for next generation magnetic data storage products and beyond. Theadvantages of PMR associated with a soft underlayer (SUL) from PMR mediacan reduce both sensor track width (MRW) and magnetic write width (MWW)significantly. A single pole writer combined with a soft magneticunderlayer also has the intrinsic advantage of delivering higher writefield than LMR heads. However, side fringing from a trailing shield PMRhead is substantially larger than in LMR. The large side fringing forPMR heads is a primary concern for the push to higher track density(TPI) and is a major constraint to PMR extendability.

A conventional PMR write head as depicted in FIG. 1 typically has a main(write) pole 10 with a small surface area (pole tip) at an air bearingsurface (ABS) 5 and a flux return pole (opposing pole) 8 which ismagnetically coupled to the write pole through a trailing shield 7 andhas a large surface area at the ABS. Magnetic flux in the write polelayer 10 is generated by coils 6 and passes through the pole tip into amagnetic recording media 4 and then back to the write head by enteringthe flux return pole 8. The write pole concentrates magnetic flux sothat the magnetic field at the write pole tip at the ABS is high enoughto switch magnetizations in the recording media 4. A trailing shield(not shown) is added to improve the field gradient in the down-trackdirection.

In FIG. 2, a top view is shown of a typical write pole layer 10otherwise known as the main pole layer or main write pole. The writepole 10 has a narrow section 10 n that extends a neck height (NH)distance from the ABS plane 5-5 to a plane 3-3 parallel to the ABS wherea middle section 10 m having sides 10 s flares out at an angle θ from adashed line 11 that is an extension of one of the sides of narrowsection 10 n. There is also a third main write pole section 10 r thathas one end at the plane 9-9 where the flared sides 10 s terminate andextends a certain distance away from the plane 9-9 in a directionperpendicular to the ABS.

To achieve high areal recording density with PMR technology, keyrequirements for the PMR writer design are to provide large fieldmagnitude and high field gradient in both down-track and cross-trackdirections. In practice, these two requirements are often traded offwith each other to balance the overall performance. There are twoapproaches to achieve these requirements. One approach involvesoptimizing the geometry of the main write pole such as modifying thevalues for NH and flare angle θ. A short NH or large θ can increasewrite field magnitude effectively. However, too short of a NH leads toproblems of meeting process tolerance during manufacturing while toolarge of a flare angle θ may cause a large amount of adjacent trackerasure (ATE) because of a large fringe field. In today's commercial PMRwriter products, NH is generally above 0.1 micron and flare angle θ iskept less than 45 degrees. A second design approach involves applyingmagnetic shield structure in the vicinity of the main write pole asdescribed by M. Mallary in “One Terabit per Square Inch PerpendicularRecording Conceptual Design”, IEEE, Trans. Magn., Vol. 38, July, 2002.To further improve cross-track field gradient, a full side shield writerstructure is used to limit the excessive fringe field onto the adjacenttrack. Depending on the spacing between the side shield and the writepole, field magnitude could drop below the minimal performancerequirement. As a result, flux intensity will be reduced at the ABS andwritability will decrease.

As recording density keeps increasing, the trade-off between writabilityand field gradient becomes more challenging. Therefore, all the designelements must be integrated and optimized simultaneously to achieve bestperformance. Unfortunately, none of the prior art structures providesatisfactory control of field magnitude and field gradient in both thedown-track and cross-track directions. Therefore, an improved writestructure is necessary to achieve the high performance required foradvanced devices with narrow track widths and high recording density.

A search of the prior art revealed the following references. U.S. PatentApplication 2007/0253107 shows that a trailing shield and side shieldmay be a single piece. A non-conformal side gap is depicted where theside gap length between a side shield and pole tip section narrows withincreasing distance from the ABS.

In U.S. Patent Application 2008/0100959, a conformal side gap isillustrated where the side gap is larger than the write gap.

SUMMARY OF THE INVENTION

One objective of the present invention is to provide a PMR writerstructure that decreases side fringing fields while maintainingsufficient write field magnitude for applications with high recordingdensity and having narrow track widths.

Another objective of the present invention is to provide a PMR writerstructure with an integrated side shield in which the side shield andtrailing shield are formed in the same process step to avoid fluxchoking at a side shield/trailing shield interface.

According to the present invention, these objectives are achieved in animproved PMR design that includes a main pole layer with a non-conformalside shield and a trailing shield structure that improves writabilityand cross-track field gradient. The main pole layer is comprised of anarrow section having one end (pole tip) at the ABS plane and a secondend along a second plane that is parallel to the ABS and located a neckheight (NH) distance from the ABS when observed from a top view. Theremainder of the main pole layer extends away from the second plane andmay be comprised of a second flared section with an end that adjoins oneend of the narrow section at the NH distance and with two sides thatflare outward at an angle θ from the two sides of the narrow section.The two flared sides adjoin the main body of the main pole proximate toa throat height distance from the ABS. The main body of the write polemay have a rectangular shape or other shapes used in the art.

Viewed from the ABS plane, the pole tip has a leading or bottom edgedisposed above a substrate, a top or trailing edge opposite the leadingedge, and two sides that connect the leading and trailing edges. The topedge typically has a greater width than the bottom edge and determinesthe track width. The main pole layer including the narrow section isformed in an opening within a first dielectric layer that may becomprised of alumina. In one aspect, a second dielectric layer is formedon the sidewalls and bottom of the opening to adjust the track width. Amain pole seed layer is disposed on the thin second dielectric layerwithin the opening. The remainder of the opening is comprised of a mainpole layer material such as CoFe that is disposed on the main pole seedlayer and has a top surface coplanar with the first dielectric layer. Awrite gap layer made of a dielectric material such as alumina is formedon the narrow pole section, flared pole section, and above a portion ofthe main pole layer adjacent to the flared pole section.

Adjacent to the first dielectric layer adjoining the sides of the narrowpole section and a portion of the flared pole section is a thirddielectric layer. A side shield layer adjoins the third dielectric layerand extends from the ABS to a certain distance from the ABS that ispreferably greater than the neck height. The first, second, and thirddielectric layers formed between the narrow pole section and a sideshield comprise a side gap. A key feature is that the side shield layeris not conformal to the narrow pole section. In other words, a side ofthe side shield layer facing the narrow pole section and flared sectionis not parallel to the nearest side of the aforementioned main polelayer sections. Therefore, the side gap distance between the top edge ofthe pole tip and the side shield is less than the side gap distancebetween the bottom edge and the side shield. A trailing side shield isformed on the write gap layer along the ABS and adjoins the side shieldlayer to give a contiguous magnetic layer on three sides of the narrowrectangular pole section. The trailing shield may have a rectangularshape with one long side formed in a cross-track direction along the ABSand two short sides perpendicular to the ABS.

In one embodiment, the side shield layer is comprised of a full sideshield having a section along each side of the narrow pole section andpole tip where each section has a top surface, bottom surface, and athickness that is essentially the same as the thickness of the pole tipin a down-track direction. The top surface of the side shield may becoplanar with the top surface of the narrow pole section or slightlyoffset below the top surface. Likewise, the bottom surface of the sideshield may be coplanar with the bottom surface of the narrow polesection or slightly offset above the bottom surface.

The PMR structure may be fabricated by depositing a first dielectriclayer made of alumina on a substrate. The substrate may be a top shieldlayer in a read head, and also serves as a flux return pole and thebottom layer in a write head portion of a merged read/write head. Anopening is formed in the first dielectric layer by a conventionalphotolithography and etching process and corresponds to the intendedshape of the main pole layer from a top view. The opening typically hassloped sidewalls and includes a trench perpendicular to the ABS. Asecond dielectric layer made of alumina or the like may be deposited byan atomic layer deposition (ALD) method on the first alumina layer andcovers the sidewalls and bottom of the opening. Thereafter, a platingseed layer such as Ru which also functions as a chemical mechanicalpolish (CMP) stopper layer is deposited by an ion beam deposition (IBD)method on the second dielectric layer. Next, the main pole layer iselectroplated on the plating seed layer to fill the opening. Following afield etch, an alumina layer is deposited on the main pole layer andfield area to fill in the troughs in the uneven top surface of the mainpole layer. A chemical mechanical polish (CMP) process is performed andstops on the plating seed layer above the first dielectric layer therebyplanarizing the main pole layer to be coplanar with the plating seedlayer. Subsequently, an ion beam etch (IBE) may be employed to taper themain pole layer in a region adjacent to the ABS.

From a side view along a plane that is perpendicular to the ABS, themain pole layer is typically tapered such that the thickness of thenarrow pole section adjacent to the ABS is less than the thickness ofthe main pole layer which is formed a greater distance than the throatheight from the ABS. The first dielectric layer is exposed along the ABSand for a certain distance towards the back end of the main pole layer.A second photopatterning and RIE sequence is performed to removeportions of the exposed first dielectric layer except a region proximateto the narrow pole section and an adjacent portion of the second flaredsection and thereby creates a side shield cavity on either side of thenarrow pole section and along a portion of the flared section.

A third dielectric layer may then be deposited by an ALD process on thesubstrate, over the first dielectric layer, and on the main pole layer.The portion of the third dielectric layer disposed on the main polelayer serves as a write gap. The resulting sidewalls of the thirddielectric layer proximate to the narrow pole section are essentiallyvertical or may be slightly sloped. A third photoresist patterning andIBE sequence is employed to form an opening in the write guard above aportion of the main pole layer where a top yoke will subsequently bedeposited. Thereafter a seed layer is deposited on the write gap and onexposed portions of the main pole layer. A magnetic layer is depositedon the seed layer and comprises a side shield on opposite sides of thenarrow pole section, a trailing shield above the write gap and adjacentto the ABS, and a top yoke in the opening on the main pole layer.

An opening is formed in the magnetic layer between the trailing shieldand top yoke and exposes the seed layer above a horizontal section ofthe write guard. The seed layer in the opening is removed by an IBEprocess. Next, a physical vapor deposition (PVD) is used to fill theopening between the trailing shield and top yoke with alumina or anotherinsulator material. A CMP process is performed to planarize the aluminalayer to be coplanar with the top surfaces of the trailing shield andtop yoke. The remainder of the write head is formed by conventionalsteps known to those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a conventional PMR writer showingthe main write pole, flux return pole, magnetic recording media, andcoils that generate magnetic flux.

FIG. 2 is a top view showing a main pole layer of a conventional PMRwrite head that has a narrow pole section adjacent to the ABS and alarger section with sides that flare outward at an angle θ from thesides of the narrow pole section.

FIG. 3 is a cross-sectional view from an ABS plane that shows aconformal side shield design that was previously fabricated by theinventors.

FIG. 4 is a cross-sectional view of an integrated side shield structurein a PMR write head with a non-conformal side gap according to oneaspect of the present invention.

FIG. 5 is a top view of the integrated side shield structure in FIG. 4where the top shield and overlying layers in the write head have beenremoved.

FIG. 6 is a cross-sectional view from an ABS that shows the formation ofan opening in a first dielectric layer which corresponds to the intendedshape of the main pole layer to be deposited in a later step accordingto one embodiment of the present invention.

FIG. 7 is a cross-sectional view after a second dielectric layer, seedlayer, and main pole layer are sequentially formed in the opening inFIG. 6.

FIG. 8 is a cross-sectional view after a field etch, alumina depositionand CMP process are performed to planarize the main pole layer in FIG.7.

FIG. 9 is a cross-sectional view of the PMR write head in FIG. 8 afterthe seed layer is removed above the first dielectric layer by an IBEprocess.

FIG. 10 is a top view of the PMR write head in FIG. 9, and FIG. 11 is aside view of the PMR write head in FIG. 9.

FIG. 12 is a top view of the PMR write head in FIG. 10 after a sideshield cavity is formed on either side of the pole tip at the ABSaccording to the present invention.

FIG. 13 is a cross-sectional view of the PMR write head in FIG. 12 thatshows the first dielectric layer is trimmed to create a side shieldcavity.

FIG. 14 is a cross-sectional view of the PMR write head in FIG. 13 aftera third dielectric layer is deposited on the substrate, main pole, andfirst dielectric layer.

FIG. 15 is a side view of the PMR write head in FIG. 14 following anetch to remove a portion of the third dielectric layer (write guard)above the main pole layer.

FIG. 16 is a cross-sectional view of the PMR write head in FIG. 15 aftera magnetic layer is deposited to form side shields, a trailing shield,and a top yoke.

FIG. 17 is a side view of the PMR write head in FIG. 16 showing anopening formed above the write guard and between the trailing shield andtop yoke.

FIG. 18 is a top view of the PMR write head in FIG. 17 after the seedlayer is removed within the opening between the trailing shield and topyoke.

FIG. 19 is a cross-sectional view from the ABS of the PMR write head inFIG. 18 after the trailing shield is planarized.

FIG. 20 is a side view of the PMR write head in FIG. 19 following analumina deposition to fill the opening between the trailing shield andtop yoke.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a PMR writer comprised of an integrated sideshield structure with a non-conformal side gap where the side shield anda trailing shield form a single piece on a write gap. The drawings areprovided by way of example and are not intended to limit the scope ofthe invention. The exemplary embodiment depicts a PMR writer comprisedof a merged read/write head configuration. However, the PMR writer ofthe present invention is not limited to a merged PMR read-write head andmay encompass other PMR writer configurations as appreciated by thoseskilled in the art.

Referring to FIG. 3, a conformal side shield structure previouslyfabricated by the inventors and disclosed in patent application Ser. No.12/072,272 is depicted. Side gaps 16 are made of alumina and aredisposed on a substrate 15. A side shield 19 is formed adjacent to aside gap 16 and has a sidewall 19 s that is essentially parallel to thenearest side 17 s of the pole tip section 17. Thus, side gaps 16 have aconstant width s. Above the pole tip section is a write gap 18 and atrailing shield 20. In the conformal side shield structure, there issignificant main pole flux leakage to the side shield 19 that will causelower overwrite. Thus, we are motivated to modify the side shield designand thereby minimize the flux leakage from the main pole to the sideshield by enlarging side gap width. Furthermore, a fabrication schemewhich requires fewer steps than used to make a conformal side shieldstructure is desirable.

Referring to FIG. 4, a cross-sectional view from an air bearing surface(ABS) illustrates a non-conformal integrated side shield PMR head 30according to one embodiment of the present invention. There is a mainpole layer 35 which has a pole tip exposed at the ABS. The pole tip iscomprised of a bottom edge 35 a, a top edge 35 b, and two sides 35 s andis adjoined on the bottom and two sides by a seed layer 34. The pole tipand seed layer 34 are enclosed in an alumina layer 49 that is typicallycomprised of a plurality of alumina layers including a write gap betweenthe top edge 35 b and trailing shield 38 as explained in a latersection. The alumina layer 49 separates the side shield 37 from asubstrate 31 that may be a separation layer formed between a read headand a write head in a merged PMR read-write head, for example. Aluminalayer 49 also separates the side shield 37 from seed layer 34 and poletip sides 35 s. Side shield 37 with thickness r and trailing shield 38form a single magnetic piece and are adjoined along a plane 50-50. Trackwidth TW is the width of the top edge 35 b along the ABS.

It should be understood that the main pole layer 35 has a top surface 35b that extends from the ABS to the back end of the device 35 e asillustrated in FIG. 5. There are additional layers above the trailingshield 38 in the write head which are not shown in order to simplify thedrawing (FIG. 4). Furthermore, the substrate 31 may be part of a slider(not shown) formed in an array of sliders on a wafer. After the PMRwrite head 30 is completed, the wafer is sliced to form rows of sliders.Each row is typically lapped to afford an ABS before dicing to fabricateindividual sliders that are used in a magnetic recording device.

Returning to FIG. 4, a key feature of the present invention is that theshape of the side gap which is the portion of the alumina layer 49between side shield 37 and seed layer 34 does not conform to the slopeof sidewalls 35 s in pole tip 35. In other words, the side gap distancea of about 0.06 to 0.5 microns, and preferably 0.10 microns, proximateto the top edge 35 b is less than the side gap distance b of about 0.1to 0.55 microns, and preferably 0.14 microns, proximate to the loweredge 35 a. In particular, sidewall 37 s of side shield 37 is notparallel to sidewall 35 s of the main pole layer 35. In the exemplaryembodiment, sidewall 37 s forms an angle β of 90° or slightly less than90° with respect to the plane 50-50 that is parallel to the plane of thesubstrate 31 and orthogonal to the ABS. Write gap distance between topedge 35 b and trailing shield 38 is between 300 and 500 Angstroms. Poletip thickness p is typically between 0.15 and 0.25 microns.

Referring to FIG. 5, a top view of the PMR write head in FIG. 4 isdepicted in which all layers above the main pole layer 35 are removed tosimplify the drawing and show the layout of the side shield 37 withrespect to the main pole layer 35 near the ABS 40-40. The length d ofthe side shield 37 is about 0.1 to 0.5 microns and extends from the ABS40-40 toward the backend 35 e of the main pole layer 35. Note that theside gap distance a is uniform between side shield sidewall 37 s andseed layer 34 as a function of distance from the ABS. In anotherembodiment, the side gap distance a (and b not shown) may becomeslightly larger as a function of distance from the ABS. In general, aconstant side gap distance a (and b) is preferred as a function ofdistance from the ABS since that configuration is easier to reproduce ona manufacturing scale.

In the exemplary embodiment, the seed layer 34 conforms to the shape ofthe main pole layer and flares at an angle α outward along the flaredsides 35 s with respect to a plane (not shown) that is parallel to theplane 41-41. The plane 41-41 is perpendicular to the ABS 40-40 andbisects the main pole layer 35. The bend in seed layer 34 which givesrise to angle a typically occurs at a distance n from the ABS where n isless than the neck height NH where the narrow pole section adjacent tothe ABS 40-40 joins the flared sidewalls 35 f of the main pole layershown with a top surface 35 b. Likewise, side shield sidewall 37 sflares outward at an angle a with respect to a plane (not shown) that isparallel to the plane 41-41 at a distance n from the ABS 40-40.

Returning to FIG. 4, in a preferred embodiment the side shield 37 may beconsidered a full side shield as the thickness r of the side shield isessentially equal to the thickness p of the pole tip 35. In oneembodiment (not shown), the top surface of side shield 37 along plane50-50 may be coplanar with top surface of the main pole layer (edge 35b) and the bottom surface 37 a of the side shield may be coplanar withthe bottom surface of the main pole layer (bottom edge 35 a). In analternative embodiment, the top surface of side shield 37 lies on plane50-50 and is offset by a certain distance above the top edge 35 b.Optionally, the bottom surface 37 a may be offset above the bottom edge35 a by a certain distance. The offset of the top surface along plane50-50 and bottom surface 37 a may be from 0 to about 0.15 microns fromthe top edge 35 b and bottom edge 35 a, respectively, along thedown-track direction which is along the z-axis. The main pole layer 35is preferably comprised of CoFe or an alloy thereof while side shield 37and trailing shield 38 are preferably comprised of CoNiFe or the like.

Referring to FIGS. 6-20, the present invention also encompasses a methodof fabricating the aforementioned non-conformal integrated side shieldstructure. With regard to FIG. 6 which is a view from the ABS, a firstdielectric layer 32 is deposited on substrate 31 that was describedpreviously. The first dielectric layer 32 may be comprised of aluminaand may be formed by a physical vapor deposition (PVD) process, forexample. An opening 39 is generated by a conventional photoresistpatterning and etching sequence and corresponds to the intended shape ofthe main pole layer to be deposited in a subsequent step. The etchprocess may involve reactive ion etching (RIE) if a photoresist mask isemployed or ion beam etching (IBE) when a metal mask is used.Optionally, first dielectric layer 32 may be made of silicon oxide orother insulation materials employed by those skilled in the art.

Referring to FIG. 7, a conformal second dielectric layer 33 made ofalumina or the like is deposited by an ALD method within the opening 39and on first dielectric layer 32. The second dielectric layer 33 isbetween 100 to 300 Angstroms thick and is used as a conformal liner inthe opening 32 in order to adjust the track width. Next, a seed layer 34that also functions as a CMP stopper in a later processing step isdeposited on second dielectric layer 33 by ion beam deposition, forexample. The seed layer 34 is preferably Ru and also conforms to theshape of the opening 39. Thereafter, the main pole layer 35 iselectroplated on the seed layer 34 to fill the opening 39 and results inan uneven top surface 35 s having a trough 35 t in regions above filledopening 39.

Referring to FIG. 8, a field etch which is a chemical etch is performedto remove the electroplated layer in regions outside the photoresistmask which covers the device area. Next, an alumina layer (not shown) isdeposited by a PVD method on the main pole layer and adjoining regionsin order to fill in the troughs 35 t within the uneven top surface 35 s.A CMP process is then used to form a planar surface where main polelayer 35 is coplanar with the seed layer 34 that remains above firstdielectric layer 32.

Referring to FIG. 9, a second photoresist patterning and etchingsequence is performed to remove a portion of the seed layer 34 along theABS. In one embodiment, an IBE process is employed with a verticaldirectionality to remove the seed layer 34 in exposed regions.Subsequently, a second IBE process with an angular component is used toetch the main pole layer 35 in exposed regions adjacent to the ABS andthereby produce a taper such that the thickness of the narrow polesection and second flared section is less than that of the main body ofthe main pole layer.

In FIG. 10, a top view of the PMR structure in FIG. 9 is depicted andshows a plane 41-41 that bisects the main pole layer with top surface 35b and is orthogonal to the ABS 40-40. A portion of first dielectriclayer 32 and adjacent regions of seed layer 34, second dielectric layer33, and the narrow section of main pole layer 35 b are uncovered by theaforementioned IBE process. Thus, a rectangular shaped section of seedlayer 34 has been removed in a region that extends a distance d of about0.1 to 0.5 microns from the ABS 40-40. All of the narrow section of themain pole layer top surface 35 b and a portion of the flared sectionbounded by flared sides 35 f are uncovered. Note that seed layer 34remains in filled opening 39 that is bisected by plane 41-41.

Referring to FIG. 11, a side view of the PMR structure in FIG. 10 isshown along the plane 41-41. Note that the thickness of the main polelayer gradually increases with increasing distance m from the ABS 40-40.The angle φ formed by the intersection of the ABS 40-40 and top surface35 b adjacent to the ABS is about 30 to 40 degrees.

In FIG. 12, a top view is shown of the PMR structure in FIG. 10 after athird photoresist patterning and etch sequence is employed toselectively remove exposed portions of first dielectric layer 32 butleaving a strip having a width w along the second dielectric layer 33 oneither side of the plane 41-41. Note that the first dielectric layer 32bends at an angle α away from the plane 41-41 at a distance (n in FIG.5) from the ABS slightly less than the neck height NH where sides 35 fintersect with the narrow pole section. The width w is constant withincreasing distance from the ABS 40-40 and is between 0.03 and 0.47microns depending on the track width.

Referring to FIG. 13, a cross-sectional view of the PMR structure inFIG. 12 is illustrated. Portions of the substrate 31 are exposed as aresult of the previous first dielectric layer trim etch. The firstdielectric layer 32 has a thickness t and may have sidewalls 32 s thatare vertical or slightly sloped away from the pole tip 35.

Referring to FIG. 14, a third dielectric layer 42 that may be comprisedof alumina is preferably deposited by an ALD method on substrate 31,first dielectric layer 32, and on main pole layer 35. Third dielectriclayer 42 has a thickness h of 300 to 500 Angstroms and typically hassidewalls 42 s that conform to the sidewalls 32 s. The horizontalportion of the third dielectric layer 42 formed above the main polelayer 35 serves as a write gap. In one embodiment, the dielectric layers32, 33, 42 are all comprised of alumina. In another aspect, one or moreof the dielectric layers 32, 33, 42 may be comprised of anotherdielectric layer that is not alumina.

Referring to FIG. 15, a side view of the PMR structure in FIG. 14 isshown after a fourth photoresist patterning and etching sequence is usedto form an opening 43 in the write gap 42 above the main pole layer 35and exposes a portion of the top surface 35 b where a top yoke will bedeposited in a later step. The write gap 42 extends for a distance m+cof about 3 microns from the ABS 40-40.

Referring to FIG. 16, a trailing shield seed layer (not shown) isdeposited on the third dielectric layer 42 including the write gapportion thereof and on a portion of main pole layer 35 at a distancegreater than m+c from the ABS 40-40. Thereafter a magnetic layer 44comprised of a front section 44 s adjacent to ABS and a back section 44y (FIG. 17) above the main body of the main pole layer 35 iselectroplated using a method known to those skilled in the art. Frontsection 44 s comprises side shield 37 below plane 50-50 and trailingshield 38 above plane 50-50. Side shield 37 and trailing shield 38 areconsidered self-aligned since they are a single piece and are formedduring the same process step. A key feature is that the side walls 37 sof side shield 37 do not conform to the sidewalls 35 s of main polelayer 35 as mentioned previously. In other words, sidewall 37 s is notparallel to the nearest sidewall 35 s.

Referring to FIG. 17, a side view of the PMR structure in FIG. 16 isshown along the plane 41-41 that bisects the main pole layer 35 after aphotoresist layer (not shown) is removed by a conventional strippingprocess. There is an opening 45 separating the trailing shield 38 (infront section 44 s) from the top yoke (back section 44 y). Opening 45which is a trench from a top view (not shown) is formed by removing theaforementioned photoresist layer that occupied the opening during theelectroplating of magnetic layer 44. The trailing shield seed layer 44 ais shown on write gap 42 at the bottom of opening 45. The distancebetween the ABS 40-40 and the opening 45 is defined as the throat height(TH).

Referring to FIG. 18, a top view of the PMR structure in FIG. 17 isillustrated after the trailing shield seed layer 44 a is removed fromwithin opening 45 and seed layer 34 is removed from the perimeter ofmain pole layer 35 by an IBE process. Second dielectric layer 33 is nowshown along the outer edge of the main pole layer top surface 35 b.First dielectric layer 32 surrounding the main pole layer 35 is alsouncovered by the IBE step. The trailing shield 38 has a length d whichis equivalent to the throat height from the ABS 40-40 toward the backend 35 e of the main pole layer 35.

Referring to FIG. 19, a fourth dielectric layer 46 such as alumina isformed in the opening 45 by a PVD method, for example. A CMP process maybe used to planarize the fourth dielectric layer 46 to be coplanar withtrailing shield 38 and top yoke 44 y.

According to the exemplary embodiment in FIG. 20, a view from the ABS isshown of the PMR structure in FIG. 19 where the dielectric layers 32, 42are both alumina and combined into one dielectric layer 49. In anotherembodiment shown in FIG. 4, all three dielectric layers 32, 33, 42 arecomprised of the same insulating material such as alumina and aredepicted as a single dielectric layer 49. In all embodiments, the sidegap is represented by the distance between sidewall 37 s and seed layer34 and is non-conformal as defined previously. Moreover, the portion ofdielectric layer 49 between trailing shield 38 and the plane includingtop edge 35 b is the write gap. Thickness k of top shield 38 in the downtrack direction is between 0.25 and 0.85 microns.

We have found the non-conformal integrated side shield PMR structure asdescribed herein results in reduced flux leakage from the main polelayer to side shield and reduced side fringe fields that enable highertrack density and overwrite enhancement compared with earlier sideshield designs. The integrated side shield configuration eliminates ATEcaused by flux choking at a side shield and trailing shield interfacesince the aforementioned shields are formed as a single piece. Bettercross-track profile is also achieved compared with prior art designs.The fabrication process is compatible with existing production methodsand does not require investment in new equipment. Furthermore, thefabrication sequence is completed with fewer steps than prior artmethods that form conformal side shields.

While this invention has been particularly shown and described withreference to, the preferred embodiment thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade without departing from the spirit and scope of this invention.

1. A perpendicular magnetic recording (PMR) head, comprising: (a) a mainpole layer having a narrow pole section with two sides and a pole tip atan ABS plane, a top surface terminating at a top edge at the pole tip,and a bottom surface terminating at a bottom edge at the pole tip, and asecond section adjoining the narrow pole section and formed a certaindistance from the ABS wherein the second section has two sides thatflare out at a certain angle from the two sides of the narrow polesection at an end opposite the ABS; and (b) a shield structure comprisedof: (1) a trailing shield that is separated from the top surface of saidnarrow pole section and a portion of the second section by a write gap,and adjoins a side shield on opposite sides of the narrow pole section;and (2) a side shield having a section formed on each side of the narrowpole section and a portion of the second section, and separated fromsaid narrow pole section and second section by a side gap layercomprised of a dielectric material wherein each side shield section hasa sidewall facing the narrow pole section such that a first side gapdistance between said top surface and the sidewall is less than a secondside gap distance between said bottom surface and the sidewall, saidfirst and second side gap distances are constant with increasingdistance from the ABS along the narrow pole section and a portion of thesecond section.
 2. The PMR head of claim 1 further comprised of a topyoke formed on the main pole layer and separated from the trailingshield by a dielectric layer that is disposed on the write gap.
 3. ThePMR head of claim 1 wherein the side gap is comprised of alumina, thefirst gap distance is between about 0.06 and 0.5 microns, and the secondgap distance is from about 0.1 to 0.55 microns.
 4. The PMR head of claim1 wherein the write gap is comprised of alumina or another dielectricmaterial and has a thickness of about 300 to 500 Angstroms.
 5. The PMRhead of claim 1 wherein the side shield is a full side shield having abottom surface and a top surface wherein the bottom surface of the sideshield has an offset of 0 to about 0.15 microns above the bottom surfaceof the narrow pole section and the top surface of the side shield has anoffset of 0 to about 0.15 microns above the top surface of the narrowpole section along a down-track direction.
 6. The PMR head of claim 1wherein the side shield and trailing shield are comprised of CoNiFe andmain pole layer is comprised of CoFe.
 7. The PMR head of claim 2 whereinthe trailing shield has a side along the ABS and extends a throat heightdistance of about 0.1 to 0.5 microns in a direction perpendicular to theABS and towards the top yoke.
 8. The PMR head of claim 1 wherein thenarrow pole section and second section are tapered at an angle φ ofabout 30 to 40 degrees with respect to the ABS.
 9. The PMR head of claim1 wherein the trailing shield has a thickness along a down-trackdirection of about 0.25 to 0.85 microns.
 10. A method of forming a PMRhead on a substrate, comprising: (a) depositing a first dielectric layerhaving a top surface on a substrate and forming an opening withsidewalls and a bottom therein that corresponds to the shape of a mainpole layer to be deposited in a subsequent step; (b) sequentiallydepositing a stack of layers on said first dielectric layer that fillssaid opening; said stack of layers comprises a lower second dielectriclayer; a seed layer on the second dielectric layer; and a main polelayer with a bottom surface and two sidewalls contacting the seed layerwherein said main pole layer includes a narrow pole section terminatingat an ABS and a second section having flared sides adjoining the narrowpole section at an end opposite the ABS; (c) planarizing said stack oflayers along a top surface of the seed layer to provide a planar topsurface of the main pole layer, and then removing a portion of said seedlayer to expose a top surface of the first dielectric layer within acertain distance of the ABS; (d) removing exposed portions of the firstdielectric layer except within a certain distance of the narrow polesection and second section; (e) depositing a write gap layer on thefirst dielectric layer and main pole layer, said write gap, firstdielectric layer, and second dielectric layer together form a side gapon either side of the narrow pole section and a portion of the secondsection; (f) removing the write gap layer over a portion of the mainpole layer where a top yoke is to be deposited in a subsequent step; (g)depositing a magnetic layer on the write gap and main pole layercomprising: (1) a side shield having a sidewall on either side of thenarrow pole section and along a portion of the second section, andadjacent to said side gap wherein a first side gap distance between eachside shield sidewall and main pole layer sidewall along the top surfaceof said narrow pole section and second section is less than a secondside gap distance between each side shield sidewall and main pole layersidewall along the bottom surface of said narrow pole section and secondsection; 2) a trailing shield formed above a top surface of said narrowpole section; and (3) a top yoke formed on a portion of the main polelayer; and (h) forming a dielectric layer between said trailing shieldand top yoke.
 11. The method of claim 10 wherein said substrate is a topshield layer in an adjoining read head and the first dielectric layer iscomprised of alumina.
 12. The method of claim 10 wherein the seconddielectric layer is comprised of alumina and is deposited by atomiclayer deposition (ALD), the seed layer is comprised of Ru and is laiddown by an ion beam deposition method, and the main pole layer is formedby electroplating.
 13. The method of claim 10 wherein the seed layer isplanarized by a chemical mechanical polish (CMP) process and is removedby a photoresist patterning and etching sequence for a certain distanceof about 0.1 to 0.5 microns from the ABS.
 14. The method of claim 10wherein the write gap layer is comprised of alumina and has a thicknessbetween about 300 and 500 Angstroms.
 15. The method of claim 10 whereinthe first side gap distance is between about 0.06 and 0.5 microns andthe second side gap distance is from about 0.1 and 0.55 microns.
 16. Themethod of claim 10 wherein the top yoke is comprised of CoFe and thetrailing shield and side shield are comprised of CoNiFe.
 17. The methodof claim 10 wherein the trailing shield has a thickness from about 0.25to 0.85 microns along a down track direction.
 18. The method of claim 10wherein the first side gap distance and second side gap distance areconstant with increasing distance from the ABS, or where the first sidegap distance and second side gap distance become larger with increasingdistance from the ABS.
 19. The method of claim 13 further comprised ofan ion beam etch to form a tapered main pole layer adjacent to the ABSsuch that the top surface of the narrow pole section and a portion ofthe second section form an angle φ of about 30 to 40 degrees withrespect to the ABS.
 20. The method of claim 10 wherein the dielectriclayer formed between the top yoke and trailing shield is comprised ofalumina and is coplanar with the top yoke and trailing shield.